

Re: [K12OSN] Data Storage - Redundancy and Backup Suggestions

On Thu, 3 May 2007 17:38:57 -0700 (PDT), Nick Fenger wrote
> Hello fellow K12ltsp'ers,
> Currently, all of my student's files (and some of mine) are spinning on an old 
> 80GB drive in the smb-ldap PDC with no backup and no redundancy. I can barely 
> sleep at night.
> We are starting a online student portfolio project next year that will add 
> lots of data that needs to be safely stored, backed up, etc...
> Any suggestions for size, type of drives, should I stick them in the PDC and 
> just use software RAID or do I need some kind of Hardware solution? Should I 
> buy some kind of external drive array? How will I know if something goes 
> wrong? and what is the best way to backup all of this data?
> We are a single site independent charter school with a maximum enrollment of 
> 320 students K-12.
> Thanks in advance for your suggestions,

I am guessing that speed at this point isn't an issue if you are getting by with a
single 80GB IDE.  But if you are adding much more data in the future you may start to
see performance hits with a single IDE where you don't right now.  My suggestion would
be to add in a PCI RAID card to handle some redundancy and fail over.  I would think
that if you were happy with a single IDE in the past a SATA card would still meat your
budget needs and be fast enough.  If you have the money I would recommend SCSI, but that
would add some extra stress on the budget.  If you just want redundancy get a card that
can mirror (RAID 1), if you want to be safe on the speed side get a card that can handle
striped mirrors (RAID 0+1 or RAID 10, mirrored stripes or striped mirrors respectively).
 I am not sure how many SATA RAID cards handle RAID 0+1 or RAID 10 so that may put you
into the SCSI realm.  You could go with a RAID 5 but my experience is that the
redundancy is great, but the speed isn't quite there.  I recommend hardware RAID
whenever possible, I am not much of a fan of software RAID.  If your PDC is what
currently contains your /home directory, then I would put the drives in the PDC.  I
recommend putting your OS on a separate drive and running your /home alone on the RAID.
 You could easily move your data by adding the RAID Array and mounting it temporarily as
/newhome then rsync /home to /newhome, then remount the array as /home.  Very easy way
to add the new drives but not have to mess with your server at all.  Also then you can
enable disk quotas on the /home drive.

But first, BACKUP YOUR DATA!  You should not sleep at night until you get a backup!  I
hate to shout, but I see users lose their data every day.  Get a backup.  If you have to
move over a network share, plug in a temporary USB drive, clone with some sort of magic
device, whatever, get a backup.  After you have the backup, get a good nights sleep and
then mess with adding new drives.

As far as a permanent solution, either add in a large IDE drive, or get yourself a large
external USB drive and schedule some rsync's or whatever you desire.  I usually
recommend maintaining a few backup sets.  If you have the money get a drive large enough
to hold nightly incremental backups and a weekly full backup.  If you can, store a
separate nightly backup for each night of the week.  Backups aren't always for hardware
failure.  Mine get the most use via user mistakes.  On our main school server I store a
full month of backups by day.  Then when a student or teacher realizes 7 days from now
that they accidentally deleted some project that took them 1 month to create, I can go
back 7 days and get it for them.  If you only have one backup set, you lose that
ability.  The more backup sets, the farther back you can go.

Hope that helps.

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